Differences in relative DNA content between human peripheral blood and bone marrow subpopulations–consequences for DNA index calculations

By sequentially staining for leukocyte differentiation antigens with monoclonal antibodies and for stainable DNA content with propidium iodide, we have evaluated the DNA ratios of normal peripheral blood and bone marrow subpopulations. In 19 peripheral blood samples the relative DNA content of the monocytes was higher than that of other subpopulations, with highly significant differences between the DNA ratios of the CD14+ monocytes, on the one hand, unlabeled controls, CD3+ T‐lymphocytes, and CD20+ B‐lymphocytes, on the other. In bone marrows from 16 healthy volunteers, the relative DNA content of the myelomonocytic subpopulations was higher than that of the T‐lymphocytes with significant differences between the CD3+ lymphocytes, on the one hand, and the CD14+ monocytes, the CD13+ and CD33+ immature myeloid, the NAT9+ mature myeloid, and the AS‐E1+ nucleated erythroid subpopulation, on the other. Since a mixture of peripheral blood mononuclear cells or T lymphocytes from healthy volunteers is often used as an external standard for DNA ploidy determinations, these data suggest that such a procedure could result in an overestimation of the DNA indices of most of the bone marrow subpopulations. Instead, we suggest the use of the DNA ratio of the CD14+ subpopulation from peripheral blood as standards for ploidy determinations for the myeloid bone marrow subpopulations. © 1993 Wiley‐Liss, Inc.